Russian minnows Krasny Yar pulled off one of the biggest shocks in club rugby by beating holders Stade Francais 34-29 in the opening round of matches.
Krasny Yar, founded in 1969 and making their debut in European competition, stunned their illustrious Pool Four rivals in the Siberian city of Krasnoyarsk as former Wasps flanker Viktor Gresev scored two of their five tries.
French Top 14 side Stade Francais, who beat Gloucester in last season’s final at Murrayfield in May, led 12-5 in the first half, but Krasny Yar hit back to lead 24-17 at the interval and held on for a famous victory.
French winger Julien Arias opened the scoring with the first of his two tries, while Tony Ensor, Terry Bouhraoua and Karim Qadiri all touched down for the visitors.
But first-half tries from Azamat Bitiev, Gresev, Sione Fukofuka and Andrei Mahu put the Russians in front at half-time and Gresev went over for his second with 14 minutes remaining.
Also in Pool Four, Richard Cockerill's Edinburgh secured an impressive 37-14 win against London Irish at the Madejski Stadium with two first-half tries from centre Solomoni Rasolea putting them in control.
Connacht's Pool Five rivals Worcester registered their first win since April in all competitions after overcoming the early loss of England centre Ben Te'o to beat Brive 30-20 at Sixways Stadium in their opening match.
Te’o was forced to withdraw early on due to an ankle injury before Worcester hooker Joseph Taufete’e scored a first-half hat-trick.
Worcester prop Ethan Waller registered his first try for the club and new signing Jono Lance kicked two penalties and two conversions.
Newcastle beat Pool One rivals Newport Gwent Dragons 32-27 in a thriller at Kingston Park, where a late converted try from backrow Mark Wilson and Toby Flood's penalty edged the home side to victory.
